- § 37. Meaning of implication
- § 38. Asserted and unasserted propositions
- § 39. Inference does not require two premisses
- § 40. Formal implication is to be interpreted extensionally
- § 41. The variable in formal implication has an unrestricted field
- § 42. A formal implication is a single propositional function, not a relation of two
- § 43. Assertions
- § 44. Conditions that a term in an implication may be varied
- § 45. Formal implication involved in rules of inference

§ 38 n. 2. Frege (loc. cit.) has a special symbol to denote assertion. ↩

§ 45 n. 1. Logic, Book II, Part I, Chap. II (p. 227) ↩

The Principles of Mathematics was written by Bertrand Russell, and published in in 1903. It is now available in the Public Domain.